


Fall into Grace

by ohjustdisarmalready



Series: The Road Goes On [9]
Category: Undertale (Video Game)
Genre: Alternate Universe - Horrortale (Undertale), Alternate Universe - Underfell (Undertale), Developing Friendships, Fluff and Angst, Gen, Horrortale Papyrus (Undertale), Horrortale Sans (Undertale), Implied/Referenced Cannibalism, Regular Normal Sans Undertale, Underfell Frisk (Undertale), Underfell Sans (Undertale), mild horror themes
Language: English
Status: Completed
Published: 2021-03-05
Updated: 2021-03-05
Packaged: 2021-03-19 00:42:25
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,741
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29866566
Author URL: https://archiveofourown.org/users/ohjustdisarmalready/pseuds/ohjustdisarmalready
Summary: In canon Whither Then, Underfell Frisk falls out of Underfell and immediately into Underswap. But what if Underswap isn't the universe they hit first?
Relationships: Frisk & Sans (Undertale)
Series: The Road Goes On [9]
Series URL: https://archiveofourown.org/series/1790866
Comments: 10
Kudos: 21





	Fall into Grace

**Author's Note:**

  * For [Empty_Geas](https://archiveofourown.org/users/Empty_Geas/gifts), [bluerose2017](https://archiveofourown.org/gifts?recipient=bluerose2017).



> This is **very much an AU** of Whither Then. The mechanics of the universe work differently, front to back. Given that, here are some assumptions you can make:  
> -Frisk's fall into a universe constitutes a RESET. Memories disappear, but that universe's "true" timeline still happened.  
> -The ambient magic of a given Underground doesn't change on a RESET. Much like Underfell felt different from Underswap, a RESET Horrortale would feel different from canon Undertale, despite everything being visibly identical. Essentially, its "genre" is still the same.  
> -Part of Horrortale's premise is that its CORE malfunctioned; therefore, we can assume that its CORE is more delicate than those of other universes. In this fic, Frisk's arrival is enough to jar that malfunction into happening earlier.
> 
> **Briefing:**  
>  Horrortale is a divergence from canon Undertale's Neutral route. Frisk kills the king, crosses the barrier, and never comes back. The human SOULs have vanished. After the Underground is sent into turmoil, the CORE starts breaking down. From this scarcity, hunger starts to become widespread. In some iterations, monsters eat other monsters (or monster dust) to survive. In any case, Sans and Papyrus turn to killing and eating humans who fall in order to keep as many people alive as possible. Sans is given a massive head wound by Undyne after a conflict between her and Papyrus, and has trouble with information processing and retention, in addition to his eyelights disappearing. One of them is replaced, and the other is not; Sans develops a habit of tugging on the empty socket when he's thinking or grounding himself. You may want to google "horrotale sans and papyrus" to get an idea of what they look like.
> 
> Since this universe is getting RESET, things don't look like they do in Horrortale, but given the changes that remain even after the RESET, monsters begin adapting into a compromise between their current circumstances and the way they changed in their alternate future. Obviously Sans doesn't have a massive head wound, but his complex and rapid-fire attacks may begin to favor slow but overwhelming force instead, for example.

Grillby polishes a glass with his glass-rag. This shouldn’t be an odd occurrence—he does it every day. He does it every day. He can’t remember a day in the past decade that hasn’t involved polishing at least one glass, whether it’s because he needs to or just as a habit. The action isn’t as unfamiliar and out-of-place as it seems. It’s not inappropriate or outright ludicrous for him to be keeping his own establishment as clean as he always does. There’s no other vital, life-saving task that needs to be done, because of course, he doesn’t need to save his own life. There’s nothing endangering it. He’s just polishing a glass. That’s normal.

He doesn’t want to open today. He has an odd feeling that he doesn’t want to see anyone. He has an odd feeling that if he doesn’t open, he will hear murmurs outside, be torn on whether to investigate or not, because he has nothing—he will have nothing—and the decision will be taken from him. The doors will break in and a flood of monsters will gush through the front, knocking aside tables and breaking chairs, searching, rummaging, he won’t have what they’re asking for, there are too many—and then in an instant, smothered. Nothing more.

It’s a disconcerting thought to have on this normal morning of a normal day. He must have had some deeply disturbing nightmares last night.

The Underground itself feels different. Like there’s something they can’t come back from.

A strange feeling, to be sure.

Grillby is no slouch in combat, though; and he doesn’t fear his neighbors, all of them friendly monsters who would rather Fall Down quietly than risk hurting someone. His odd dreams are just that—dreams. Impossibilities.

All the same, the atmosphere is tense. It seems as if every eye in Snowdin is watching him as he opens up for the day.

* * *

Frisk lands in a patch of flowers that seems just like the one they first fell in, not so long ago. The atmosphere is subtly different, but close enough to being the same, and in any case they have better things to worry about than the lack of dust in the air. They dodge immediately as they come to their senses, waiting for a follow-up attack that doesn’t come.

They gain their bearings and realize it’s not going to come. Whatever Sans did, he’s gone now. He didn’t follow them.

Abandoned, Frisk moves along. It’s the only thing they can do.

* * *

Sans very nearly kills Frisk when he first sees them.

He doesn’t say so, but he wants to kill them. He wants to kill them so badly. Frisk is already scared of him enough that when he appears just on the other side of the Ruins door, standing in the middle of that path and just staring them down, they almost turn back around and hide. They want to run away from him. They don’t want him to hurt them again.

They don’t try to escape, in the end. Miss Toriel, in this strange dream of a world, is so nice; and she asked them not to come back. They can’t hurt her like that.

They inch out from the protective covering of the huge, old door, and ease into Sans’s line of sight entirely. He stares at them fixedly, wildly. His grin is huge. His eyes are wide and very, very bright.

Frisk waits to die.

When they flinch, Sans smiles.

* * *

“you ever get the feeling,” Sans says, “like there’s something you just can’t remember? some whole life, where you became some other person, and now that it’s over, you’re still not who you used to be?”

Frisk shakes their head. They hope that this Sans isn’t like the real Sans at all. If this Sans is different from what Real Sans was, then maybe he won’t…

“you’re awful quiet,” Sans says. He brings his hand up to his eye socket, then grimaces when he touches the rim of it, like he’s touched something that he didn’t think would be there. He lets it drop. “maybe i’m not the only one who changed, huh?”

Frisk looks away, uncomfortable. They don’t want to have changed. They don’t want to be somebody else. They want to be themself.

“heh. don’t tell me you hit your head or something. wouldn’t that be funny?”

Frisk nods, but they don’t think it would be funny at all.

* * *

Sans doesn’t so much ask as tell Frisk to come sleep on his couch. He would hate for them to wander off and disappear, he said, but he said it like an accusation. Like he’s keeping his enemies close.

Frisk doesn’t sleep. They know he’s gonna kill them. They’re so sure he’s gonna kill them.

Halfway through the night, Sans appears in front of them, with one eye all flared up in blue and yellow and one eye vanished. He tugs on the empty socket, casting long shadows over his face. It looks like it hurts.

Frisk flinches and lets out a tiny, hurt sound. This is when they die. They’re gonna come back but he’s still gonna kill them.

He stares them down. His expression is fevered and pitiless. He looks insane.

Frisk looks back. They watch each other, Sans and Frisk, in the kind of dark that’s only possible far under the ground. The only light anywhere is from Sans’s flashing eye. It’s hypnotic.

Frisk is frozen in place.

Eventually, it’s light again, and Papyrus comes downstairs to interrupt their “weird staring contest.” He makes spaghetti, but it doesn’t taste bitter and it doesn’t cut up their mouth. He and Sans both watch intently as Frisk eats every scrap.

Papyrus seems happy. Frisk doesn’t die.

* * *

“did you actually fall and hit your head or something?” Sans asks, apropos of nothing.

Frisk looks at him. He’s glaring at them a little, because that’s how this version of Sans always looks at them—like they’ve dealt him some personal slight that’s always gonna be at the front of his mind when he looks at them, but he’s having a hard time hating them when they’re right in front of him. It would be easier from a distance, maybe.

Then again, Real Sans didn’t need any distance at all to hate them. Frisk is glad this Sans is honest about what he must have felt all along.

“is that why you don’t talk now? didn’t you used to talk?” Sans asks. He looks like he has a headache.

Frisk shrugs. They’re not sure why he’s asking all these questions. Sans is usually happy to sit by and let information come to him.

“huh,” Sans says. “well. that sucks for you.”

All the same, something seems different after that.

* * *

Sans gets the message from Alphys. No text, just a picture message of way too many red lights and errors. It’s the CORE. It’s failing.

The dread that reaches up through his SOUL is terrifying. Being able to process all the different errors at once is weird. He doesn’t have to concentrate hard and digest them one at a time, they’re all just there. He doesn’t get headaches like he thinks he should, these days.

The human is here. The human is here, but the CORE is still failing.

It’s not supposed to happen like this. It’s not supposed to happen, right…?

* * *

When Sans has done all he can, the CORE is still failing. Alphys is frantically looking at workarounds, and he has faith that she’ll find something, but the CORE was a miracle. It was a work of genius. Alphys has maybe a month to come up with its equal.

Sans looks at his notes.

_the human left us. killed asgore. took all the souls. we have nothing. is this really the best ending…?_

The horror creeping from the entry tells its own story. The words look naïve—fumbling thoughts from a monster who didn’t see that he was doomed.

Then again, is this Sans’s position any different?

* * *

The kid seems off. Every time he looks at them, it’s like something is immediately wrong. It’s right in his face, as plain as the black-and-red striped sweater they’re wearing. His instincts insist they’re a different person entirely, some new friend or foe ~~or food~~ that he’s totally failed to evaluate.

They’re terrified of him.

They should be.

* * *

Sans sees another FIGHT come to a head at the shop. The bunny and hamster monsters look like they’re going to kill each other over a loaf of bread. He ignores the guilty, desperate urge to take it himself while they’re distracted.

He’s not like that. If it came to it, he would make sure his neighbors were fed before himself. He’d find a way, somehow. Monsters are generous and compassionate by nature—he’s not going to take something that someone else needs just because he needs it, too. He doesn’t deserve to have it more than they do. It’s not wasted if it goes to them. He’s not giving up something he needs to survive.

The Underground used to be a cheerful place, with pastels and ambient humor covering up desperation. Now it’s just desperation. Even the snow seems to gnaw away at his bones.

The CORE is failing, and Sans has taken to shutting down every use of power that isn’t absolutely essential. He covers up his civic-minded sabotage with little signs. “under maintenance.” He thinks those signs might stay there forever, long after there’s anyone to read them.

Alphys hasn’t told anyone else, yet. It’s only going to get worse.

* * *

Frisk can see Sans getting tenser and tenser. He wakes them up some nights, taking inventory of the fridge and muttering to himself under his breath.

One night, they sit up to ask him why he does that. His eyes dart to focus on the movement, tight and small.

Frisk freezes.

Sans looks thoughtful and not altogether sane.

“Sans?” they try to whisper, but all that comes out is a tiny rasp of breath.

He blinks.

“…go back to sleep, kiddo,” he says. “s’alright. i got this.”

Frisk creeps to the kitchen instead. They lean on him drowsily as they look at the fridge, trying to see what he sees.

Sans looks at it, too. It’s exactly the same as it was an hour ago when he checked it then. There’s plenty of food for three people, but not enough to last. Not enough if they can never get any more.

There’s never gonna be enough. But grocery shopping has come to be kind of a tense thing, these days. Even if they don’t know why, people are possessive over food. Some part of them knows that the Underground is _hungry_. It’s never going to be satisfied, no matter what.

Sans can see the writing on the wall. They have to get out of here.

* * *

Frisk thinks Sans hates them a little less. He sits down with them one night.

“look,” he says. “things are gonna get…bad here. pretty soon.”

He touches his cheekbone, like he does sometimes when he’s trying to tug on his eye but he can’t because there’s still an eye there.

“you’re probably gonna wanna go.”

Frisk blinks. Is he kicking them out?

“just, when you do…don’t take the other souls. ok? please, kid, i’m begging you here. don’t take them. we need those. i know they’re human like you, and all, but…if we don’t have those, then we can’t get out. if something goes bad, we can’t escape. we need them.”

Frisk doesn’t understand. They can’t take a human SOUL; they already have one. They don’t know what Sans is talking about.

“…you’re really not the same, are you? you’re just…” Sans looks at them thoughtfully, but not like he’s thinking about the best way to kill them. He’s just thinking.

“…welp. thing is, you could still totally screw us over. and, i mean, i’ve been thinking about it. i kinda get it—they’re human, you’re human, you don’t want them hanging in jars and getting experimented on forever. but. we need them. ok? promise me you won’t take them when you go.”

It seems important to him. Frisk holds out a hand to shake.

Sans takes it. They promise.

* * *

“hey, kid, so, remember a few days ago when we talked about how you’re leaving soon?”

Frisk looks up at Sans. They do remember. They kind of don’t want to leave. Their Sans pretended to love them and then hated them and tried to kill them; this Sans hated them a lot but now he likes them, right? He gives them food and tells them things are ok. That means he likes them. He must.

Frisk has finally convinced themself to stop flinching when he moves. They want to stay with him. They think he’s decided not to kill them. Papyrus has decided not to kill them. His traps only aim for gentle dismemberment now.

This world is as violent as their own, deep down, but it pretends not to be very politely. Frisk doesn’t mind. They’ve made friends with everyone except the king, and not a single monster has killed them since. They want to stay.

Sans says, “yeah. we’re moving that up. you’re leaving today.”

Frisk doesn’t want to go.

“seriously, kid. things are about to get dicey, and you’re made of meat. i can give you a lift to the palace, but you’ve gotta get gone.” Sans’s left eye darts around. His right eye keeps flickering in and out of existence, like it’s not sure if it should be there or not.

He says, “just, please don’t screw us over on this. i’m trusting you, alright? remember what you promised.”

Frisk doesn’t want to go.

“ok. right. we’re gonna skip some stuff and bring you straight to the king ‘cause we’re running low on time. and, uh, i really shouldn’t be wasting magic. and it’s not gonna matter soon anyway. end of civilization just ruins everybody’s plans, doesn’t it?”

Sans is trying to get rid of them and they don’t want to go.

Frisk is scooped up in an instant by someone behind them, and immediately they’re being carried away fast. They look over at Sans, who looks absolutely flabbergasted that someone just picked him up, too. It’s kind of a funny look on a monster who weighs slightly more than a bowling ball.

“WHAT A WONDERFUL DAY FOR A WALK! WE’RE GOING RIGHT NOW IMMEDIATELY.” Papyrus sounds anxious. He’s sprinting much faster than Frisk could.

“…bro?” Sans seems surprised still.

“WOW ISN’T IT SCENIC? I LOVE WATERFALL. YOU KNOW WHAT I LOVE MORE? THE BARRIER! LET’S GO VISIT IT ON OUR LOVELY PRE-PLANNED WALK THAT WE ARE TAKING AS A FUN FAMILY OUTING. THIS IS FINE AND NOT SCARY AT ALL. RIGHT, SANS?” Papyrus jumps straight over the gap that Frisk would otherwise be stumped by. Nothing snaps its jaws shut behind them. Nothing is right on their heels.

Or at least, Frisk can’t see what’s hunting them.

Sans goes back to scanning their surroundings. “you got it, bro. this is super relaxing. basically a spa day. hey, kid, you got any pickles that could fit over my eyes?”

Frisk thinks they hear something down a corridor. Papyrus shifts their head to be hidden in his shoulder, and no matter how much they squirm he won’t let them down to investigate.

Frisk knows what it meant when the other Papyrus would pick them up and not let them down. They go still and very quiet and no matter what, they don’t look up.

Papyrus whispers to them, “If there happened to be anything to fear, which there isn’t! But if there were then you would still not have to fear, because I would keep you safe. So…don’t be afraid of anything, basically!”

If Papyrus is protecting them, they’ll be okay. They hold on and wait for the palace.

* * *

Sans sees the sky for the very first time. The real first time, he’s sure of it.

It’s so big. It’s so big, and open, and beautiful. There’s so _much_ , all around them—life and space and light. It’s fresh and new. It doesn’t scrabble hungrily at his bones, sapping energy and thought. It’s beautiful. It’s so alive.

He turns around to Frisk, because—

He turns around and they’re gone.

* * *

* * *

One universe over, Sans is afraid.

That universe was safe. It was supposed to be safe. Anything has to be better than the hellhole he lives in, right?

But then the whole alternate universe went dark.

The other machine is down. That would be fine, but there’s also no wireless cameras, no Undernet, no phone calls…nothing is sending a signal for him to tap into. It’s like the whole Underground is gone. The glimpses he can get are empty. Sans had to tap into human signals to make sure the world still existed.

His machine hums and strains. He’s set it to scan every bit of white noise it can find, desperately searching for some life. Did monsters go extinct?

No, says his machine, because all of a sudden he’s picked up a massive surge in magic. It’s beyond anything he’s ever seen—like every monster in existence put together their power, all at once. Maybe even more powerful than that.

_no._

His sibling is pretty hard to kill. They can’t have died in this peaceful, utopian…

Besides that flash of magic, the Underground is nearly a dead zone—even the ambient magic isn’t what it should be. It doesn’t seem like a utopia. If anything, it seems like a wasteland.

Sans grabs a particular notebook from the back of a drawer. He’d put the idea of following the kid over away, because it’d probably kill him to try, but now he’s gotta rearrange his priorities. If there’s nothing for him to reach over there, he’ll walk over and put it there himself. He’ll get to where he sent them.

He has to know. If all he gets is a pile of dust for his trouble, at least he’ll have dusted everyone who let them die. Too much of a coward to kill the monsters of his own Underground—but Angel help these other monsters, because Sans doesn’t have anything to lose. Not if they’ve killed the only person who might still love him.

It takes barely half a day. The portal is open, following the human’s path through the multiverse. Either they’ll have opened the road enough for him to make it, or he’ll be dead too quick to know the difference.

He pauses before he walks in. Papyrus would be furious with him if he went. The risks are outright suicidal.

If Papyrus wanted a vote, then he shouldn’t have left. Sans has nothing left to keep him in this world.

Sans walks through the portal.

* * *

* * *

(Far away in the future, Frisk tells Just Sans, “He’s a lot like you, like, he looks _just_ like you. He has the same clothes and his magic is pretty much the same, I think. He’s so nice—I can’t wait for you to meet him! He was the first other Sans I met, and I was pretty nervous at first, but he was so nice to me. I really think I would be a different person if I hadn’t met him. He, uh…he helped me a lot, with…stuff. Like, with trying to go from my world to worlds that aren’t like mine.”

Just Sans says, “i thought that was the dancer guy who taught you that stuff?”

Frisk flushes a little. It’s kind of embarrassing to recall how petrified they were of Sans as a general concept, after leaving home the way they did. Or just…how sure they were that a peaceful world must be a trick. How naïve it was to believe that there wasn’t a world without LOVE.

“Yeah, but…he taught me more about…well, he was the very first other Sans I met, right? Shy taught me about how to act with universes that were really different from mine, but this Sans, he really…I was…” They draw on their DETERMINATION, such as it is. Talking about this stuff is hard and embarrassing, but Just Sans is their best friend. They can be honest.

“I really wasn’t ready to believe that people would just…not kill each other. Even when they wanted to. But he just…never killed anybody. Even when he was mad. It sounds like a low bar, but I think…I think he had really good reasons to be really mad, and he still never hurt anybody. Does that make sense? I don’t know how else to explain it, but he was…really gentle with me. And I was really little back then. It meant a lot.”

Just Sans softens—he gets it, sort of. He’s not from a world like theirs, but he understands what it’s like to need any kind of lifeline and then suddenly get pulled all the way up from the edge.

“He, uh. He helped me like how I helped you. I mean not exactly, but…I thought he was gonna kill me, and it turns out he wouldn’t hurt a fly. He’s really…”

“hey,” Just Sans says. “i get it. he’s important to you. i’m sure i’ll like him. he sounds like a real gentle guy.”

Fisk nods gratefully. “He really is. You’ll love his brother, too, he’s really cool! Thank you, Sans—are you ready?”

“aye-aye,” Just Sans says with a lazy salute.

“Here goes,” says Frisk, and opens the door.

In front of them is another Sans, who could be this Sans’s twin except for how he’s about twice his size and his magic slinks around in ambush. The energy holding his joints together is nearly nonexistent, with most health put aside in favor of hypervigilance and excessive force. Sans’s first instinct is to grab Frisk by the SOUL and shortcut them both to somewhere safe, and then maybe cross a few streams to throw off their scent. The other Sans looks kind of like he could eat both of them for breakfast.

But of course. Of course this is the person Frisk has decided is harmless.

Yeah, that sounds about right. Sans shrugs off the feeling of imminent doom and ambles into the little home after them. The things he does for Frisk.)

**Author's Note:**

> This whole story sprouted from [this comment thread](https://archiveofourown.org/comments/398262162) by Empty_Geas, and was encouraged by bluerose2017 on tumblr, so many thanks to both of them! I love hearing theories and spinoff ideas, and I really do love writing soft Horrortale content, so this was a really fun little side project to do. I was trying to do a bit of a new writing style, too, so it was a great chance to see how that works for me! I challenged myself to keep it to 2000 words. Challenge failed, obviously, but it still taught me a lot! Thank you for sharing your thoughts with me :) and I hope y'all enjoyed exploring this little what-if!


End file.
